Today the Redhill Brook runs through the gap in the Greensand Ridge on its way to join the Salfords Stream and the River Mole to the south.

A settlement was formed here in part of the rural parishes of Reigate Foreign and Merstham when a turnpike road was built in 1818.

The gap through the Greensand Ridge at Redhill was a major advantage for routing a railway from London to Brighton.

[citation needed] Richard Carrington, an amateur astronomer, moved to Redhill in 1852, and built a house and observatory.

The site suited an isolated observatory, being on a spur of high ground surrounded by lower fields and marsh.

Here in 1859 he made astronomical observations that first corroborated the existence of solar flares as well as their electrical influence upon the Earth and its aurorae.

Some of Pullen's ship models, designs and artwork used to be on display at the town's Belfry Shopping Centre, but have now been moved to the Langdon Down Museum in Teddington.

[17] In 1868 Alfred Nobel demonstrated dynamite for the first time at a Merstham quarry, two miles north of Redhill.

Built on a rise to the east of the town, and overlooking the railway station and the countryside around, it had a swimming bath, a gymnasium, tennis courts (asphalted and grassed), an external recreation ground as well as covered playgrounds, 21 pianos, a clock turret, a chapel and a dining room both capable of seating 600, a bakery, a steam laundry, an infirmary, an isolation hospital, and extensive gardens and orchards, all in property of 17½ acres.

Holmethorpe can refer to two neighbouring developments, one residential, the other commercial/industrial and separated by the west track of the Brighton Main Line directly north of Redhill.

A Holmethorpe Industrial Estate member's organisation exists to provide security to and advertise recruitment among its 66 businesses and to work on traffic and local authority planning matters.

[23] Redstone Hill is above the Royal Mail sorting office and depot, centred around one of three Redhill conservation areas, across the station using the A25 or subway from most of the town.

[citation needed] Deep underneath the conservation area non-stopping services of the east branch of the Brighton Main Line run.

Fengates is a Georgian three-storey building built of red brick with grey headers and a moulded band above the second floor.

The disproportionately large St. John's church was built in anticipation of the development of a town in the East of Reigate Foreign close to the railway station that opened in 1841.

In 1844, after the church's construction, the railway station was closed and a new one opened about a mile to the North, around which Warwick Town and then Redhill developed.

John Loughborough Pearson remodelled it following its 1842-3 construction by James T Knowles (senior), retaining only the aisles added in 1867 by Ford & Hesketh.

Pearson was awarded the RIBA Royal Gold Medal in 1880 and is remembered for a series of exceptionally fine churches.

At this junction, on the south side in the middle of the street Blackstone Hill, is Richard R Goulden's Shaw's Corner War Memorial, a Grade II listed grand base and statue: a bronze figure on a square-set tapering stone plinth, of a man, carrying a child in one arm, and holding a flaming torch aloft with the other.

At the top of the plinth is the inscription: In memory of the men of Reigate and Redhill who fought and gave their lives in the Great War 1914–1919On its other sides are the capitalised words Courage; Honour; and Self-Sacrifice.

[33] These buses provide connections to Reigate, Sutton, Epsom, Caterham, Oxted, Croydon, Dorking, Guildford, Gatwick Airport, Crawley and East Grinstead.

[34] The town has a distinctive red-brick complex called the Warwick Quadrant, which houses the Harlequin Theatre and Cinema, and the public library, as well as Sainsbury's and other shops.

[38] SES Water, Santander Consumer Finance, AXA breakdown assistance, Travelers Insurance, and Aon plc Risk Services have their headquarters in the town.

[40] For some central government statistical purposes, Redhill and Reigate are classified as a subdivision of the Crawley Urban Area.

The data in each ward and overall for these combined showed a proportion of rented residential property and of social housing close to the average in South East England and to that of the local authority, significantly greater in Redhill West than in Redhill East where 21.8% of property was rented from a registered social landlord or directly from the local authority.